St Andrew's and St George's Church, built to an unusual oval design by Major Andrew Fraser of the Royal Engineers, opened in 1784 as St Andrew's Church. It was the first church in Edinburgh's New Town, located in George Street, built there at the suggestion of Sir James Hunter Blair (1741-87), previously a Lord Provost of the city. In James Craig's original plan for the New Town this church should have been located on the east side of St Andrew Square, but this site could not be acquired from its owner Sir Lawrence Dundas, who had built himself a fine mansion there. Its mirror St George's Church was built in its intended location on the west side of Charlotte Square (originally St George's Square).
St Andrew's church is notable for being at the location of the 'Disruption' of the Church of Scotland, when a third of the ministers attending the General Assembly of 1843, held within the church, walked out to form the Free Church of Scotland under the leadership of Thomas Chalmers.
The congregation of St Andrew's combined with the nearby St George's Church in 1964, the latter building becoming West Register House.